problem upgrading gtk2

[Michael Thon]

When I try to upgrade gtk2 I get the following error:

     /bin/sh: line 1: gtkdoc-rebase: command not found

and I am unable to upgrade the package. This happens whether I use  
"sudo port upgrade gtk2" or "sudo port -f upgrade gtk2".  "port  
outdated" says that I have 2.12.1_0 installed and 2.12.3_0 is the  
latest version. I don't know what gtkdoc-rebase is.  is it part of the  
gtk-doc package?  That package is not installed on my system.
cheers
Mike